Novel Molecular Genetic Approaches for the Prevention and Treatment of Parkinsons

描述（申请人提供）：帕金森病（PD）是一种由中脑多巴胺神经元神经退行性变引起的运动障碍。然而，在帕金森病和帕金森病动物模型中，这些细胞的一个亚群相对幸免——那些从内侧腹侧被盖区（VTA）投射到腹内侧纹状体（VMS或伏隔核内侧壳）的细胞。该突起还包含许多多巴胺神经元，这些神经元表达泡状谷氨酸转运蛋白（VGLUT2）并共同释放兴奋性神经递质谷氨酸。由于VGLUT2和囊泡单胺转运蛋白（VMAT2）似乎定位于VMS中突触囊泡的重叠群，谷氨酸的囊泡共同进入可能通过增加囊泡pH梯度（DpH）赋予神经保护作用。更大的DpH可以增加多巴胺的囊泡储存，将多巴胺和其他潜在的细胞毒性VMAT2底物隔离到囊泡体中，从而减轻其毒性。本研究的第一个目的是通过选择性条件敲除小鼠和病毒表达策略测试VGLUT2是否在PD的MPTP病变模型中具有神经保护作用。在PD或PD病变模型中，多巴胺神经元丢失后，基底神经节中多巴胺感受性中棘神经元（MSN）的输出失调。特别是，多巴胺D2受体的过度激活，包括间接途径的msn和随后的丘脑下核的过度兴奋，似乎是与PD相关的最严重的运动症状的原因。因此，我们将在PD损伤模型中测试将间接通路输出从抑制性到兴奋性的极性翻转是否可以恢复运动行为。这些研究将测试新的假设和神经回路中的新分子靶点（VGLUT2）。这项工作将为这些神经回路对兴奋性递质释放变化的可塑性提供重要信息，并可能为帕金森病的治疗和预防提供新方法。

DESCRIPTION (provided by applicant): Parkinson's Disease (PD) is a motor disorder brought on by neurodegeneration of midbrain dopamine neurons. However, a subpopulation of these cells is relatively spared both in PD and in PD animal models - those that project from the medial ventral tegmental area (VTA) to the ventromedial striatum (VMS or the medial shell of the nucleus accumbens). This projection also contains many dopamine neurons that express the vesicular glutamate transporter (VGLUT2) and co-release the excitatory neurotransmitter glutamate. Because VGLUT2 and the vesicular monoamine transporter (VMAT2) appear to localize to an overlapping population of synaptic vesicles in the VMS, the vesicular co-entry of glutamate may confer neuroprotection by increasing the vesicular pH gradient (DpH). Larger DpH would then be predicted to increase the vesicular storage of dopamine, serving to sequester dopamine and other potentially cytotoxic VMAT2 substrates into vesicular bodies where their toxicity is mitigated. The first aim of this proposal will test whether VGLUT2 confers neuroprotective benefits in an MPTP lesion model of PD using selective conditional knockout mice and viral expression strategies. Following the loss of dopamine neurons in PD or PD lesion models, output from the dopaminoceptive medium spiny neurons (MSN) in the basal ganglia is dysregulated. In particular, over-activation of the dopamine D2 receptor containing MSNs of the indirect pathway and consequent over-excitation of the subthalamic nucleus appear to account for the most severe motor symptoms associated with PD. We will thus test whether flipping the polarity of indirect pathway output from inhibitory to excitatory can restore motor behaviors in a PD lesion model. These studies will test novel hypotheses and a new molecular target (VGLUT2) in the neural circuitry that contribute to PD. The work will provide important information about the plasticity of these circuits to changes in excitatory transmitter release, an may lead to new approaches for the treatment and prevention of Parkinson's Disease.